How? I must know!

Aurorae are a vanilla effect.

Why would you want to remove such a beautiful spectacle?

I don't want to remove auroras entirely, just the glowy pink, orange and yellow ENB version. I LOVE the vanilla auroras

Those are vanilla too.

*sigh*

Nevermind. I'm not communicating what I want very effectively.

I've put over 100 hours into Skyrim, but after installing (and subsequently removing) ENB, the intensity and brightness of the auroras is increased to "11". I prefer vanilla. How do I get back to vanilla?

If you're still using ENB, just get the ENB Customizer: http://skyrim.nexusmods.com/mods/17400

Its a doddle to use and has settings for auroras. It wont remove them but you can at least reduce the intensity and effect contrast (under the sky category). Why would auroras still be effected if you're no longer using ENB?

Download the ENB you were using manually. Open the archive but don't re-install it; look at each file to make sure you deleted them all.

Also, check your INI files; is there a setting that makes the Auroras brighter?

There are 2 specific ENB settings for auroras (enbseries.ini in parent Skyrim directory):

AuroraBorealisIntensity=0.7
AuroraBorealisCurve=1.0

Intensity is the power of the effect. Lowering it will dim the auroras (note that if you lower it too much, it can also look weird).
Curve is the range/uniformity of the brightness. Setting it much higher than 1 might result in more intense auroras.

EDIT: If it wasn't obvious, open the enbseries.ini file in any text editor. The settings are near the bottom of the config.